White-footed mice are the principal natural reservoirs for Lyme disease bacteria. Ticks that feed on mice are highly likely to become infected, making them capable of transmitting Lyme disease to people during their next blood meal. When they feed on mice during their larval and nymphal stages, ticks are more likely to survive and molt. Ticks that feed other vertebrate host species have a comparatively lower survivorship. Consequently, we have hypothesized that the greater the abundance of mice during the midsummer peak in larval tick feeding activity, the greater the probability that questing larval ticks will encounter a mouse, and the higher the probability that they will molt into an infected nymph capable of transmitting Lyme bacteria one year later.
Our long-term monitoring of mouse abundance, tick abundance and infection prevalence in southeastern New York State supports these hypotheses. In addition, because we have demonstrated a correlation between acorn production and mouse abundance the following year, we have hypothesized that acorn abundance is a good predictor of abundance and infections prevalence of ticks almost two years in advance. This hypothesis also is supported by our monitoring data.